benjamin



(No Model.) 2 Sheets-Sheet 1.

E. B. BENJAMIN.

STATICAL ELECTRICAL APPARATUS.

Patented July 11 (No Model.) 2 Sheets-Sheet 2.

- E. B. BENJAMIN.

STATIGAL ELECTRICAL APPARATUS. No. 261,118. Patented July 11,1882.

ATTORNEYS.

N. PETERS, PhowLium n mr, wmn m, D. c.

UNITED STATES PATENT OFFICE.

EDMUND B. BENJAMIN, OF NEW YORK, N. Y.

STATICAL ELECTRICAL APPARATUS.

SPECIFICATION forming part of Letters Patent No. 261,118, dated July 11, 1882. Application filed March 24, 1882. (No model.)

To all whom it may concern:

Be it known that I, EDMUND B. BENJAMIN, of the city, county, and State of New York, have invented a new and useful Improvement in Statical Electric Apparatus, of which the following is a specification.

The object of my invention is to provide a means whereby the intensity and rapidity of the discharge of an electrical machine generating static electricity, or of an induction-coil which converts dynamic into static electricity, may be materially increased.

The invention consists in a plug, cap, shield, or cover of insulating material, which is combined with the conductor or part of the apparatus at which so-called positive electricity, or electricity of high potential, is supposed to accumulate, as hereinafter described.

In the accompanying drawings, Figure 1 is a perspective view, and Fig. 2 is a side view, of the conductors of a statical electric machine, between which the discharge takes place when the machine is operated. Fig. 3 is a face view of the conductorB in Fig. 1. Figs. 4 to 7 show my invention applied to an induction-coil. Fig. at is a face view, and Fig. 5 a side view, of the break to which the device is attached. Fig. 6 is a side elevation, and Fig. 7 is a plan, of the induction-coil and its support, with the break shown in Figs. at and 5 in place.

Similar letters of referen ce indicatelike parts.

B is the conductor on which accumulates the so-called positive or high-potential electricit-y, and A is the conductor on which accumulates the so-called negative or low-potential electricity, generated in or by the machine. These conductors are of metal, and between them the discharge passes whenever the tendency of the electricity to pass from the highpotential to the low-potential conductor is sufficiently strong to overcome the resistance of the interval of air between said conductors.

The distance over which an electrical discharge or spark will pass in air between the conductors of an electrical machine is limited by the capacity of the apparatus to generate electricity, so that as between two similar machines the one which will project a spark over a greater interval of air between its conductors or discharging-points is relatively the more powerful of the two.

I have found by experiment that the length of spark in air and the intensity and rapidity of discharge of an electrical apparatus of the character before stated can be greatlyincreased by combining with the positive or high-p0tential conductor a cap, cover, shield, or plug of ebonite, rubber, glass, or other non-conductin g or insulating material, so that said shield shall be in contact with but shall not wholly cover the face of the said conductor, and shall be placed thereon so as to be opposite the corresponding face of the low-potential conductor, and in the path normally taken by the discharge in passing through the air between said conductors. This shield is shown at O in the drawings, Figs. 1 and 2, as placed upon a conductor the end of which is of spherical form. The area of said shield should always be less than that of the face of the conductor to which it is applied, as is shown in the face view, Fig. 3. So long as this is observed I do not consider any particular relative proportion of area of shield to area of face of conductor as material.

It will be seen that the shield 0 serves the purpose of a stationary break or interrupter, and when it is made and combined with the high-potential conductors, as described, I find that it largely increases the capacity of the machine, enabling sparks of much greater length, and delivered more rapidly between the conductors, to be obtained. It also affordsmeans of producing electrical effects in moist or warm climates with much greater facility than has hitherto been possible with the class of apparatus with which the device is combined. On small static electrical machines of the Holtz and other patterns I have found that it nearly doubles the length of spark otherwise obtainable.

The theory of the operation of my invention I believe to depend upon the fact that electricity accumulates on the surface of conductors until it reaches a state of tension suflicient to overcome the resistance of the non-conductingmedium interposed between said conductor and another conductor adjacent thereto, when a disruptive discharge takes place between the two conductors. The cap of insulating material which I employ apparently prevents the overcoming of the resistance and the prodnction of the discharge until a higher degree of i tension is reached than could normally be attained, the electricity being prevented from accumulating at the portion of the conductors where the cap is located and caused to do so at or near the region surrounding said cap.

The application of my device to an induction-coil for converting dynamic into static electricity is shown in Figs. 4 to 7. The current passes by the post F to the spring A and piece 13, to the face of which last the cap 0 is attached. 1) is the induction-coil, and F is an adjusting-screw for the break-spring A. The discharge takes place between the piece B and the induction-coil 1).

What I claim as new, and desire to secure by Letters Patent, is- 

